In today's communications, digital networks transport large amounts of information. Network services can be, for example, traditional voice phone, facsimile, television, audio and video broadcast, and data transfer.
Buffers and buffer descriptors are used to convey data. Buffers store data to be transmitted or received while buffer descriptors point to these buffers. Various examples of data transmission devices and methods using buffer descriptors are illustrated in the following U.S. patents and patent applications, all being incorporated herein by reference: U.S. Pat. No. 6,212,593 of Pham et al., U.S. Pat. No. 6,735,210 of Lindeborg et al., U.S. Pat. No. 6,154,460 of Kerns et al., U.S. Pat. No. 6,298,396 of Loyer et al., U.S. patent application 2004/0073724 of Wilson et al., U.S. patent application 2002/0176430 of Sangha et al., U.S. patent application 2005/0243816 of Wrenn et al., U.S. patent application 2005/0093885 of Savekar et al., U.S. patent application 2005/0068956 of Liao et al., and U.S. patent application 2002/0161943 of Kim.
Various communication protocols as well as various management protocols were developed in order to support a variety of services and configurations.
The IEEE defined two management interface named MII management and GMII management that use a two-wire serial interface to connect between a management entity and managed physical layer (PHY) components. GMII can support faster communication protocols than the MII. An exemplary device that includes such a serial interface is described in PCT patent application publication serial number WO 01/17166 of Kalapatapu which is incorporated herein by reference.
Each PHY component has multiple registers that can be accessed by using the MII management or GMII management interface. These registers can be accessed in order to control the PHY components and gathering status from the PHY components.
The management interface includes a pair of signals (clock and information signals), a management frame, a set of registers that can be read and written using the management frames, and a protocol specification that defines the manner in which the management frame is transferred between the management entity and the PHY components. The basic (mandatory) set of registers of the MII management includes a control register and a status register. The MII management and the GMII management use the same management frames and use the same signals. The GMII management includes an additional basic register that is referred to as extended status register.
The control register is known as register 0. The status register is known as register 1. The extended status register is known as register 15. Registers 2-10 belong to an extended register set. This extended register set includes PHY identifier registers (registers 2 and 3), auto-negotiation advertisement register (register 4), auto-negotiation link partner base page ability register (register 5), auto-negotiation expansion register (register 6), auto-negotiation next page transmit register (register 7), auto-negotiation link partner received next page register (register 8), MASTER-SLAVE control register (register 9) and MASTER-SLAVE status register (register 10).
FIG. 1 and FIG. 2 illustrates the content of control register 10, status register 30 and the extended status register 50.
Control register 10 includes the following fields: reserved (not used) field 11, speed selection fields (LSB and MSB) 12 and 19, collision test enable field 13, duplex mode field 14, restart auto-negotiation field 15, isolate field 16, power down field 17, auto-negotiate enable field 18, loopback field 20 and reset field 21. These fields control the manner in which the PHY component operates.
Status register 30 includes the following fields: extended capabilities field 31, jabber detect field 32, link status field 33, auto-negotiation ability field 34, remote fault field 35, auto-negotiation complete field 36, MF preamble suppression field 37, reserved (not used) field 38, extended status field 39, 100BASE-T2 half duplex field 40, 100BASE-T2 full duplex field 41, 10 Mb/s half duplex field 42, 10 Mb/s full duplex field 43, 100BASE-X half duplex field 44 and 100BASE-T4 field 45.
Extended status register 50 includes the following fields: 1000BASE-T half duplex field 51, 1000BASE-T full duplex field 52, 1000BASE-X half duplex field 53 and 1000BASE-X full duplex field 54. It also includes reserved bits (not shown).
Fields 31-54 indicate the status of the PHY component. For example, they indicate the communication protocols it supports and the state of an auto-negotiation session conducted with that PHY component.
A single communication controller may be required to write control information to physical layer component control registers and also to read status information from physical layer component status registers. One method for doing it involved polling the status register and control registers and determining whether data can be transferred, as well as using dedicated registers within a register file to save parts of the status information or control information. Registers are more expensive than simple memory unit entries. Accordingly, using registers was resource consuming.
The polling method required a lot of processor intervention in order to know when the access is done so valid data can be read.
FIG. 3 illustrates a management frame 80. Management frame 8C is serially transferred over a first line while a second line is used to convey a clock signal. Multiple physical layer components are connected in parallel to the information line and to the clock line.
The management frame 80 starts by a preamble field 81 (can be thirty two bits long) that is followed by a two bit long start of frame indication 82 (value of ‘01’), a two bit long opcode 83 that indicate if the frame is being transferred during a read operation (from the register of the physical layer component to the management entity) or a write operation, a five bit long physical layer component address 84, a five bit long register address 85, a two bit long turnaround field 86, and a two-byte long data field 87.
The complexity of status information and control information management increases as the number of physical layer registers increase.
There is a need to provide an efficient method and device for reading status information from status registers of physical layer components.